The AT&T Picturephone: The Video Call That Arrived 50 Years Too Early

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In 1964 you could step into a booth in New York's Grand Central Terminal and see a live video feed of a friend in Chicago. You also had to reserve the slot in advance, make sure the other person travelled to a matching booth, and pay $27 for three minutes. This episode follows the AT&T Picturephone from a Bell Labs experiment in the 1930s, where Dr. Herbert Ives led more than 200 scientists, engineers, and technicians, through a mid-1950s prototype that sent one still image every two seconds, to the sleek oval Mod I shown off at the New York World's Fair and Disneyland.

The public booths closed by 1968, but AT&T concluded it had simply picked the wrong customer and aimed the redesigned Mod II at corporate offices, launching in Chicago in 1970. The engineering behind that six-inch screen was staggering, and so was the miscalculation. The company predicted one million units in service by 1980 and peaked at under 500. The reasons had less to do with physics than with how people in an office wanted to behave on a phone call, and the lessons shaped the video calling that came later.

• The first transcontinental video call ran between the World's Fair and Disneyland on April 20th, 1964.
• Booths stood in Grand Central Terminal, the National Geographic Society headquarters in Washington, and the Prudential building in Chicago, with a Washington to New York call priced at $16.
• The Mod II mounted a Plumbicon camera tube on the top lip of the screen to create the illusion of eye contact.
• Each Mod II needed three twisted pairs of telephone cable and an amplifier every single mile, since its one megahertz signal was over 300 times larger than a voice call.
• For long distance, engineers used differential pulse code modulation, sending only the differences between frames over T2 carriers.